blow off

scott markle_2

I read in a Heat-link bulletin that in low temperature systems bacteria can thrive in glycol levels below (I believe) 20%. This has to do with the fact that these systems don't hot hot enough to kill bacteria and the glycol at low concentrations can actually feed bacteria. Keep in mind that some glocol comes pre-diluted I believe the most common formulation of cryo-tec comes 70%.

A reflectometer and ph meter are almost essential tools for monitoring glycol systems. A down side in addition to the problems with ph is the slipery nature of glycol it gets past seals,valve packings and air vents and leaves a ugly corrosive stain.

HR has done a tech topic on this. http://www.heatinghelp.com/newsletter.cfm?Id=255

dmy hvac

blow off

i recently have put glycol in my friends crown boiler i filled up to about 90% glycol now his relief valved has blown off about 3 times in the past week filling a 5 gallon bucket up a little less than 1/4.i checked his expansion tank it had about 15 psi air with boiler at 20psi i also let some glycol out to bring pressure down to 15psi ive never heard of any problems with glycol building up more pressure than water he lives about an hour away am goin there tomorow to see what i can do.any suggestions i should look into id appreciate it.not sure if its automatic water feed leaking by.it is a new relief valve and is exact replacement of original.thanks

[Deleted User]

Take another expansion tank with you...

or a larger one. Glycol and water have a higher coefficienc of expansion than does just water. If not compensated for, the relief valve will do what its inteded to do...

ME

Derheatmeister

Why so much Glycol?

Why is it that you used 90% Glycol? isn't that very viscous ?.I do not like to use Glycol unless it's really needed! It lessens the heat transfer, Makes the Circs work harder,And is bad for the Expansion tank! As for the pressure on the Expansion tank that should be checked with no water/Glycol on the wet side and i keep it approx. 2psi less than the fill Pressure.

[Deleted User]

DOH...

I missed the 90 percent glycol...

Got a cat pump?

Ever smoked three pumps in one night....or was it four:-)

Yeah, for sure, dilute the glycnoids.

ME

Empire_2

90 * Glycol?

Yea, that is a bit Much. It's like trying to pump maple syrup through the lines. I'll bet you are lacking flow. Also watch you PH% when introducing glycol's as in reaks havoc on everything and most pump manufacturers have a set range for the PH level for the pumps to perform as intended. If you know you total system volume and intended temp ranges, I can look for a chart I have that may help. In fact I'll bet Brad W. probably has it.

Mike T.

dmy hvac

glycol

i used a glycol that is rated at 100% is good for 100- below zero.are all glycols the same cause ive never heard of anything bad with this kind.if so what is a rule to set the percentage for 20 or 30 below?? thanks for all your replys

Derheatmeister

Depends

Like i've said before,Is it really Needed? Is someone living in the House? are there Overhangs? Piping Close to outside Walls that can freeze?.Some times Guys just pump it into the system Because that's what we do ???.I ve seen Overpumped systems that are changing circs(Premature Failures)and the Customer Thinks is't normal!... also Think about it this Way: your System fails For what ever Reason,You never know it until you or your Customer arrives to a frozen house that has all of it's Ceilings raining into a frozen Lake that runs down the stairs like a frozen waterfall.Seen it!!!. all you have to do is get the system up and running again. the house can heatup again. but the damage is doen. makes a good Heated job for replacing all the domestic waterlines/Toilets/fixtures . How about not overpumping,Maybe protect the system only to about +5 or 0 F and offering a freeze Alarm in conjunction.?